Superfluidity in thin /sup 4/He films: Comparison of onset on particular crystal facets and on disordered substrates

Journal Article · Wed Dec 01 04:00:00 EST 1982 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00681898· OSTI ID:6235287

Hess, G B; Muirhead, R J

Superfluid flow in unsaturated /sup 4/He films on highly ordered pyrolytic graphite, (001) cleaved MgO, epitaxial gold on mica, polycrystalline gold, and glass has been studied by the heat transport technique. Using a criterion for onset suggested by the Kosterlitz-Thouless theory, we confirm that the locus of onset in the variables T and p/p/sub 0/ is substrate independent within experimental error, whereas the film thickness at onset varies widely with substrate. The reason for this is not understood. Several aspects of the Kosterlitz-Thouless theory are verified: On polycrystalline gold the film flow impedance decreases approaching the transition from the normal side, consistent with the dependence calculated by Ambegaokar et al. On the superfluid side of onset, power law relations are found between temperature gradient and current, in agreement with the prediction based on thermal dissociation of vortex pairs in the velocity field. The exponents are consistent with the expected variation of the renormalization superfluid density with coverage, including a Nelson-Kosterlitz jump smeared by finite-velocity effects. On MgO we obtain only an upper limit for the film coverage at onset; its consistency with the Nelson-Kosterlitz jump depends on the interpretation of neutron scattering data.

• Research Organization: Physics Department, University of Washington, Seattle, Washington
• OSTI ID: 6235287
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 49:5; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
CARBON
CHALCOGENIDES
ELEMENTAL MINERALS
ELEMENTS
EVEN-EVEN NUCLEI
FILM FLOW
FILMS
FLUID FLOW
FLUIDS
GOLD
GRAPHITE
HELIUM 4
HELIUM II
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALS
MICA
MINERALS
NONMETALS
NUCLEI
OXIDES
OXYGEN COMPOUNDS
QUANTUM FLUIDS
STABLE ISOTOPES
SUBSTRATES
SUPERFLUIDITY
THIN FILMS
TRANSITION ELEMENTS